Utilizing a cyclic (alkyl)(amino)carbene (CAAC) as a ligand, neutral CAAC-stabilized radicals containing a boryl functionality could be prepared by reduction of the corresponding haloborane adducts. The radical species with a duryl substituent was fully characterized by single-crystal X-ray structural analysis, EPR spectroscopy, and DFT calculations. Compared to known neutral boryl radicals, the isolated radical species showed larger spin density on the boron atom. Furthermore, the compound that was isolated is extraordinarily stable to high temperatures under inert conditions, both in solution and in the solid state. Electrochemical investigations of the radical suggest the possibility to generate a stable formal boryl anion species.

The donor properties of five different PCcarbeneP ligands are assessed by evaluation of the CO stretching frequencies in iridium(i) and rhodium(i) carbonyl cations. The ligands feature dialkyl phosphine units (R = (i)Pr or (t)Bu) linked to the central benzylic carbon by either an ortho-phenylene bridge, or a 2,3-benzo[b]thiophene linker; in the former, substituent patterns on the phenyl linker are varied. The carbonyl complexes are synthesized from the (PCcarbeneP)M-Cl starting materials via abstraction of the chlorides in the presence of CO gas. In addition to the expected mono carbonyl cations, products with two carbonyl ligands are produced, and for the rhodium example, a novel product in which the second carbonyl ligand adds reversibly across the Rh[double bond, length as m-dash]C bond to give an η(2) ketene moiety was characterized. The IR data for the complexes shows the 2,3-benzo[b]thiophene linked system to be the poorest overall donor, while the phenyl bridged ligands incorporating electron donating dialkyl amino groups para to the anchoring carbene are very strongly donating pincer arrays.

No abstract

Objectives To collect normative data and test the feasibility and reproducibility of measurement of the maxilla–nasion–mandible (MNM) angle between 16 and 36 weeks' gestation and its diagnostic ability in a group of pathological cases. Methods The MNM angle is defined as the angle between the intersection of the maxilla–nasion and mandible–nasion lines in the exact mid‐sagittal plane. After assessing reproducibility, the MNM angle was measured in 3D volumes in 241 fetuses cross‐sectionally and in 11 fetuses longitudinally. The MNM angle was then tested in 18 pathological cases with facial malformations or syndromes with specific facial features. Results The MNM angle could be measured in 92.3% of normal fetuses. Intra‐ and interobserver intraclass correlation coefficient (ICC) variability was 0.92 and 0.81, respectively. The difference between paired measurements performed by one or two observers was less than 2.5° and 3.6°, respectively in 95% of the cases. The mean MNM angle was 13.5° and did not change significantly during pregnancy (r = − 0.08, P = 0.25). The MNM angle was above the 95th centile in all cases of retrognathia and maxillary alveolar ridge interruption. The MNM angle was below the 5th centile in Apert syndrome, thanatophoric dysplasia and in two of the three Down syndrome cases. Conclusions The feasibility and reproducibility of measurement of the MNM angle is good. The MNM angle can be used to evaluate the convexity of the fetal profile by enabling an objective assessment of the anteroposterior relationship of the jaws and it may therefore be of help in the diagnosis of retrognathia, maxillary alveolar ridge interruption and flat profile. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.